1. Field of the Invention
The invention relates generally to nano-size structures, and in particular, to coated composites of magnetic nanoparticles and quantum dots, as well as methods associated with the same.
2. Discussion of Related Art
Nanoparticles are microscopic particles of matter having dimensions on the nanometer scale (e.g., less than 100 nanometers). Of particular interest are a class of nanoparticles known as quantum dots, or semiconductor nanocrystals, that exhibit properties that make them particularly useful in a variety of applications including as fluorescent probes in biological labeling and diagnostics. Because of quantum confinement effects, quantum dots can exhibit size-dependent optical properties. For example, cadmium selenide (CdSe) quantum dots can emit across the entire visible spectrum when the size of the crystal is varied over the range of from two to six nanometers.
When quantum dots are irradiated, more energy is required to promote the electrons to a higher state, leading to an increase in energy release in the form of photons and light emission in a color that is characteristic of the material. The resulting photons that are released typically exhibit a shorter wavelength than those released from a bulk form of the same material. The quantum confinement of electrons and holes in three dimensions contributes to an increasing effective band gap with decreasing nanocrystal size. Therefore, smaller quantum dots typically exhibit shorter emitted photon wavelength.
Magnetic nanoparticles are another class of nanoparticles. These particles have also generated considerable interest because of their magnetic properties and small dimensions.